Hot forming process of zinc-based coating high-strength steel

Abstract

The invention discloses a hot forming process of zinc-based coating high-strength steel. The hot forming process comprises the process steps that (1) the zinc-based coating high-strength steel is processed into a semi-finished product; (2) the semi-finished product is heated to 500-600 DEG C in an inert atmosphere, the temperature is maintained for 3-5 minutes, and then heating continues to the substrate austenitizing temperature, and the temperature is kept until the substrate is completely austenitized; (3) after the semi-finished product is moved out of a heating furnace, the semi-finishedproduct is cooled to 600-700 DEG C at the cooling speed of 30-50 DEG C / s; and (4) the semi-finished product is transferred into a stamping shaping mold to be subjected to pressure maintaining quenching treatment, the quenching temperature ranges from 450 DEG C to 650 DEG C, the quenching cooling speed ranges from 30 DEG C / s to 50 DEG C / s, And the hot forming finished product of the zinc-based coating high-strength steel can be obtained. According to the process, the alloying process of a zinc coating in the heating and cooling processes can be reasonably regulated and controlled, crack initiation and expansion of high-strength steel parts can be effectively relieved or inhibited, surface oxidation and quality are controlled, and the LMIE brittleness of liquid metal is well controlled; andthe obtained product has the advantages of high strength, good surface quality and the like.

Description

technical field [0001] The invention relates to a thermoforming method, in particular to a thermoforming process of zinc-based coated high-strength steel. Background technique [0002] With the improvement of energy saving and emission reduction, automobile lightweight and collision safety requirements, the application of ultra-high-strength steel in automobile parts is becoming more and more extensive. Due to the high strength of ultra-high-strength steel sheets, it is easy to have dimensional accuracy problems such as cracking and springback during cold forming, and it will also cause severe mold wear and tear. Especially for materials with a tensile strength higher than 1000MPa, it is difficult to process components with complex shapes and structures by traditional cold forming methods. The thermoforming process is the process of forming and strengthening the material under high temperature conditions. The obtained products have the characteristics of high strength, high...

AI Technical Summary

Problems solved by technology

However, the melting point of the zinc-based coating is low. When the heating temperature is higher than the melting point of the Γ phase in the coating, liquid zinc will exist, making it easy to appear LMIE brittle cracks caused by liquid metal during high-temperature forming.

When the heating and holding time is too long, the zinc in the coating will continue to volatilize, resulting in a decrease in the zinc content in the zinc layer, serious oxidation on the surface of the steel plate, and a decrease in corrosion resistance

If the heating temperature is too low or the holding time is too short, the complete austenitization of the substrate cannot be guaranteed, resulting in insufficient martensite structure in the steel plate after stamping and quenching, so that the product strength cannot meet the requirements

Therefore, the heating process and hot forming process system of galvanized high-strength steel will have a greater impact on the production process of hot-formed parts

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